The present invention relates to a heat exchanger and a process for producing the same. More specifically, the invention is concerned with a heat exchanger which experiences reduced deterioration in performance attributable to frosting and which can be produced with a high production efficiency.
Heat exchangers have been proposed to reduce the deterioration in performance attributable to frosting. An example of such heat exchangers is shown in Japanese Utility Model Unexamined Publication No. 50-122054. In this heat exchanger, the widths of fins are varied to be zigzag at the air inlet side of the heat exchanger so as to reduce the obstruction against the flow of air caused by frost which is formed heavily specifically at the inlet ends of the fins.
This known heat exchanger will be described hereinunder with reference to FIG. 9 which is a perspective view of the zigzag arrangement of this heat exchanger. As illustrated, the heat exchanger has a multiplicity of fins 7, 8 penetrated by heat exchanger tubes 1 which may be refrigerant tubes 1, and air flows into this heat exchanger in the direction of an arrow A. More specifically, the fins are grouped into two types: namely, fins 7 which have a greater width L2 and, hence, a greater distance between the end face 7a and the refrigerant tube 1, and fins 8 which have a smaller width L3 and, hence, a smaller distance between the end face 8a and the refrigerant tube 1. These two types of fins 7, 8 are arranged alternately and are fixed to the tubes 1.
The heat exchanger as shown in FIG. 9 can be produced by, for example, a process disclosed in Japanese Patent Unexamined Publication No. 58-110142. This process will be explained with reference to FIG. 10 which is a perspective view showing this process. A wide hoop 12 is fed in the direction of an arrow B and is cut by a press having cutting blades 10, 10a which are arranged such that pairs of wide fin 7 and narrow fin 8 are formed in a side-by-side fashion, along longitudinal lines 9, 9a of cutting. Then, the wide fin 7 and the narrow fin 8 are severed along a transverse line 11 by a cutting blade 15. A jig 14 having pins 13 receives the thus severed wide and narrow fins 7, 8 falling thereonto, with its pins 13 inserted in the refrigerant tube holes 16 formed in the respective fins, whereby the wide and narrow fins 7, 8 are stacked alternately.
In this type of heat exchanger, the deterioration of performance due to frosting is remarkably suppressed, but the efficiency of production of this type of heat exchanger is low because of the process for preparing and alternately stacking two types of fins of different widths as illustrated in FIG. 10.
The described process also suffers from a disadvantage in that, particularly when the fin of the heat exchanger is of narrow type having a single row of refrigerant tubes as shown in FIGS. 9 and 10, the refrigerant-tube holes on the fins 7, 8 cannot correctly catch and receive the pins 13 on the jig 14 so as to hinder the production, with the result that the production efficiency is impaired. This is attributable to the fact that the centroid or center of mass of one of the fins 7, 8 does not coincide with the position of the hole, due to variance in the distance between the fin end and the tube (hole).